Role of Heterogeneities in Ejecta via MD Simulation*

We investigate the shock behavior of copper seeded with heterogeneities via molecular dynamics simulations. Specifically, we aim to understand the influence of heterogeneities such as atomic defects and bubbles on ejecta production in copper. Since shock melting plays a key role in ejecta production, microstructure was previously thought to not matter, but recent results suggest that different microstructures alter the mechanism through which ejecta is produced. For example, the presence of helium bubbles near the free surface of copper has been shown to nearly triple ejecta production due to a loss of planarity at the shock front. We analyze the size and velocity distributions to understand the mechanisms of ejecta production and the influence of heterogeneities on material strength. The ultimate goal of this work is to inform and elucidate upon parallel experiments, where data collection presents a significant challenge. LA-UR-19-26660